Product Description The Aero Precision M4E1-T Complete Upper Receiver is a precision-engineered AR-15 upper assembly built for shooters who demand performance, reliability, and a lightweight profile. This complete upper pairs the renowned M4E1 Threaded Upper Receiver with the ATLAS S-ONE M-LOK Handguard and a 16" 5.56 NATO mid-length barrel, delivering a cohesive system that is ready to drop onto any mil-spec lower receiver. The upper comes fully assembled with a port door and forward assist installed. Note: This complete upper does not include a Bolt Carrier Group (BCG) or Charging Handle. Product Highlights M4E1 Threaded Upper Receiver: Forged from 7075-T6 aluminum with a hardcoat anodized finish, featuring a new enhanced forging for a billet look, laser-engraved T-marks, M4 feed ramps, and .250 takedown pin holes for a precise, dependable fit. 15" ATLAS S-ONE M-LOK Handguard: Designed with size and weight in mind, this slim handguard uses Aero Precision&';s proprietary ATLAS attachment system for a rock-solid, wobble-free connection, with QD sling sockets at 3, 6, and 9 o&';clock positions and M-LOK slots for versatile accessory mounting. 16" 5.56 NATO Mid-Length Barrel: Machined from 4150 Chrome Moly Vanadium (CrMoV) steel with a QPQ salt bath nitride finish, a 1:7 twist rate, and HP/MPI tested for verified integrity and reliable performance. Mid-Length Gas System: Provides a smoother recoil impulse compared to a carbine-length system on a 16" barrel, reducing felt recoil and extending the service life of internal components. Ready to Build: Ships fully assembled with an A2 flash hider, low-profile gas block, and mid-length gas tube installed. Compatible with mil-spec AR-15 upper receivers and barrels. Does not include BCG or Charging Handle. Specs Brand: Aero Precision MPN: APAR700305M7 UPC: 840014601585 Caliber: 5.56x45mm NATO (also compatible with .223 Remington) Platform: AR-15 Upper Receiver: M4E1 Threaded; Forged 7075-T6 Aluminum, Hardcoat Anodized Handguard: 15" ATLAS S-ONE M-LOK, Lightweight with Proprietary ATLAS Attachment System Barrel Length: 16 inches Barrel Material: 4150 Chrome Moly Vanadium (CrMoV) Steel Barrel Finish: Salt Bath Nitride (QPQ) Twist Rate: 1:7 Gas System: Mid-Length Gas Block Journal: .750 inches Gas Port: .0785 inches Barrel Threading: 1/2x28 Muzzle Device: Standard A2 Flash Hider (not pinned/welded) Feed Ramps: M4 Feed Ramp Extension Testing: HP (High Pressure) and MPI (Magnetic Particle Inspected) Tested Forward Assist: Assembled and Included Port Door: Included Finish/Color: Anodized Black Country of Manufacture: United States BCG/Charging Handle Included: No Disclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the product&';s manufacturer. ]]>